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Cushing’s Syndrome

Practice this case based on how you are assessed in your OSCEs, and use the relevant sections for general revision. 🤓

 

Doctor Instruction:


You are a doctor working in family medicine. Your next patient is Monk Keye, a 40-year-old female complaining of tiredness and low mood. Please take a history and perform a relevant examination.



 

Patient History:


Your name is Monk Keye, a 40-year-old female working as an office worker at HR of a company.


You have generally felt more tired and lowly for the past few months. You notice you have been gaining weight and feel embarrassed that you look fatter. You also feel stressed. When asked, you have been bruising a lot lately, and you have more "fat" on your face, back and neck and look rounder. When asked, you have stretch marks and weakness in your limbs. You have lost interest in sexual activity with your partner and have mood swings, making you argue a lot with him. Your menstruation has been becoming more irregular lately, but you think it's because you may be going to have menopause. You also have been drinking a lot of fluids lately as you always feel thirsty and urinate a lot as a result. Otherwise, eating and drinking well. You have poor sleep at the moment.


No headache/ visual problems or galactorrhoea. No previous fractures.


Ideas, Concerns, Expectations:

  • You think you might be having depression or just reaching menopause. You are concerned that these symptoms are affecting your life – work / social and, most importantly, with your partner! You hope to get married one day and don't want to be single again! You want to find out what is going on!


Past Medical History:

  • Hypertension, Ulcerative Colitis


Drug History:

  • On ramipril, omeprazole and on prednisolone you have been taking for a while

  • NKDA


Family History:

  • A thyroid disease, but you do not know which one.


Social History:

  • Don't smoke

  • Don't drink

  • Live with a partner

  • Independent at home


 

Examination Findings:

  • Round "moon" face with large fat build-up on the back of your neck and shoulders (buffalo hump). Your face is red and puffy (facial plethora). Acne. Central obesity. Abdominal Stiae. Reduced muscle mass in proximal limbs. Thin skin and bruising around limbs. Hirsutism may be present.


 

Differentials:

  1. Cushing’s Syndrome

  2. Hypothyroidism

  3. Depression / Anxiety

  4. Peri-menopause


 

Investigations:


Bedside:

  • Observations ( hypertension)

  • Pregnancy test (rule out physiological cause of pregnancy)

  • BM – (hyperglycaemia)

  • ECG/ Echo – (may indicate cardiac hypertrophy in Cushing’s)

  • 24-hour urinary free cortisol ( as an alternative to dexamethasone suppression) – false positive with alcohol, psychoses, exercise, anorexia, pregnancy.

  • Midnight cortisol level (salivary ) - elevated in Cushing’s syndrome


Bloods:

  • Blood gas- metabolic alkalosis in Cushing’s

  • Blood tests- FBC (high WBC in Cushing’s), U+E (K+ may be low if aldosterone is produced by an adrenal adenoma), LFT (baseline) + TFT (to check thyroid function and rule out hypothyroidism)

  • ACTH levels (Low means independent of ACTH e.g. adrenal adenoma/carcinoma/exogenous glucocorticoid use. High means dependent of ACTH e.g. pituitary adenoma/ ectopic ACTH)

  • Dexamethasone suppressed corticotropin-releasing hormone test

  • Plasma CRH – for ectopic CRH production (rare)

  • Consider DHEA levels in those with virilisation and cushingoid features– if elevated may suggest adrenal carcinoma


Dexamethasone suppression test (Low/ High dose test) – low dose test to exclude Cushing's Syndrome first – if abnormal, then high dose test is used to differentiate underlying causes of Cushing's syndrome:


Low Dose Test (1mg Dexamethasone given at night) :

  • Low cortisol (next morning): Normal

  • High/normal cortisol (next morning): Cushing’s Syndrome


High Dose test (8mg dexamethasone given at night):

  • Low cortisol (next morning): Cushing’s Disease

  • High/ Normal Cortisol (next morning) + low ACTH > Adrenal Cushing’s

  • High/Normal Cortisol (next morning) + high ACTH > Ectopic ACTH e.g. from small cell lung cancer


Imaging:

  • Xrays/DEXA scans may show osteoporosis

  • Chest CT for Small cell Lung Cancer / bronchial carcinoid tumours – to rule out paraneoplastic Cushing’s (can also occur in other endocrine tumours e.g. phaeochromocytoma, pancreatic neuroendocrine tumours, medullary thyroid cancer, gut carcinoids…etc.)

  • Abdominal CT for adrenal adenoma/carcinoma/source of ectopic ACTH

  • CT TAP – localise tumour and assess metastasis

  • MRI for pituitary adenoma

  • Octreotide scanning / PET scan – localise tumour


Special Test:

  • Consider Inferior petrosal sinus sampling (IPS) - locate the source of excess ACTH


 

Management:

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